Hydraulic riveter



Deel E92, 1944-.L H. R. FlscHERiE-l-AL 2,365,537

HYDRAHULU; ELVQETER @Trigiral HGM.. 18, 19I5,9.e Sheets-Sheet l INVENTORS HOWARD RFISCHER EDWARD W. STEVENS ATTOR NEY DSC 19, 1944 H. R. FISCHER ET AL 2,365,537

HYDRAULIC RIVETERV Original Filed Nov. 18. 1939 lO Sheets-Sheet 2 EDWARD W. STEVE NS BY Wg ML ATTORNEY D 19, 1944- H. R. FISCHER ET AL 1 2,365,537

` HYDRAULIC RIVETER Original Filed NOV. 18, 1939 l0 SheetS-Sheet .3

TRA- Y "I INVENTORS HowARD RFlscHER EDWARD w.sTEvENs 87 ATTORNEY Dec. 19, 1944.

1o sheets-sheet 4 v H. R. FISCHER ET AL HYDRAULIC RIVETER original Filed Nov. 18, 1939 Dec. 19, 1944.V H. R, FISCHER `ET AL 2,365,537

HYDRAULIC RIVETER Original Filed Nov. 18, 1939 10 Sheets-Sheet 5 l l l INVENTORS HOWARD R` FISCHER EDWARD W. STEVENS ATTOR N EY Dec. 19, 1944.

91' Q II:-

H. R. FISCHER ET AL 2,365,537

HYDRAULIC RIVETER Original Filed Nov. 18, 1939 10 Sheets-Sheet 6 @WM Mai ATTORNEY Dec. 19, 1944.

HYDRAULIC RIVETER Original Filed Nov. 18, 1939 H. R. FISCHER ET AL 10 Sheets-Sheet 7 ATTORNEY Dec. 19, 1944.

H. R. FISCHER i-:T A1.

HYDRAULIC RIVETER Oignal Filed Nov. 18. 1939 10 Sheets-Sheet 8 12055 103 l Il 775 naman M .1 14. 'S- off/ uuuelu Il al a im '[H'Ililll (L nl' lllll| IHIIIlIilIlIInIllI v INVENTORS HOWARD R. FISCHER E DWAR D W. STEVENS ATTORNEY vDefl- 19, 1944- H. R. FISCHER ET AL 2,365,537

A HYDRAULIC RIVETER .Original Filed Nov. 18, 1939 l0 Sheets-Sheet 9 F1 0 1&2 155 INVENTORS HOWARD R. FISCHER EDWARD W. STEVENS AToRN EY DeC- 19, 1944- H. R.- FlscHER ET AL 2,355,537

HYDRAUL I C RI VETER Original Filed Nov. 18, 1939 lO Sheets-Sheetl 10 TTU" INVENTORS HOWARD R.FISCHER EDWARD W. STEVENS ATTORNEY n Patented Dec. 19, 1944 HYDRAULIC RIVETER Howard R. Fischer and Edward W. Stevens, De-

troit, Mich., assignors to Chicago Pneumatic Tool Company, New York, N. Y., a corporation of New Jersey Original application November 18, 1939, Serial No. 305,204. Divided and this application August l5, 1942, Serial No. 454,973

r (Cl. 78-48) 12 Claims.

This invention relates generally to compression riveting and like machines and more particularly to a machine of this class having a portable power generating unit to which one or a plurality of riveting units may be attached.

According to a feature of the present invention, the power generating unit comprises, in addition to the hydraulic system for effecting operation of the riveting unit, a valvular controlled compressed air system for actuating the hydraulic system.

This is a division of applicati-on Serial No. 305,204, led November 18, 1939, in which the pressure fluid distributing system of the invention is claimed. This case is directed to the riveting unit and the means for operating the riveting piston therein. Adistinguishing feature of the riveter is its connection to the power generating unit by three hose lines. Through two of the lines oil is delivered to opposite ends of the piston cylinder while the third line contains compressed air. By manipulation of control means on the riveter the air in the third line is exhausted therefrom at varying rates of speed thereby to control operation of the pressure generator which initiates a flow of oil alternately through the first two lines during a riveting cycle.

The principal object of the invention is to produce a small compact riveting assembly that is completely automatic in its operation and which may be readily adapted for use in different classes of riveting work.

A more specific object of the invention is to permit control of the assembly through the rivet setting and rivet heading stages of a rivet installation by manipulation of a trigger on the riveting unit.

Another object of the invention is to construct the riveter of a plurality of sub-units which are adjustable and interchangeable to permit modil iication of the riveter in accordance with the requirements of a particular class of work.

A further object is to embody in the assembly a two-way valve mechanism for conditioning for operation alternatively e'ither of a pair of riveting units, attached to the power generating unit.

Numerous features of novelty are embodied in the machine, some of which are:

1. A compressed air distributing system by which the several steps of a riveting operation are controlled automatically, and which automatically terminates a cycle of operation;

2. An adjustable means for varying the peak pressure obtainable in the compressed air system in order that a maximum of efficiency may be attained in heading rivets of different size;

3. Automatic means, capable of operation prior to the release of the manipulative trigger, for returning the power and riveting pistons to normal position, thereby speeding up operations in which a number of rivets are headed in rapid succession; and

.4. Control mechanism associated with the hydraulic system for maintaining automatically a proper balance of oil in the various sections of the system. v

Other objects of the invention, additional features of novelty, and structural details of the machine will be more apparent from the following description when read in conjunction with the accompanying drawings, wherein:

Fig. 1 is a View, in perspective, of the power generating unit and riveting unit completely assembled and ready for operation;

Fig. 2 is a perspective view of a riveting unit of modified construction;

Fig. 3 is a view, partly in section and partly in elevation, of the power generating unit;

Fig. 4 is a view, in elevation, of the head section and a fragmentary portion of the cylinder of the power generating unit;

Fig. 5 is a view, in section, of the head of the power generating unit, and is taken substantially along the line 5-5 of Fig. 3;

Fig. 6 is a view looking downward through the base of the power generating unit and is taken substantially along the line 6 6 of Fig. 3;

Fig. 7 is a' sectional view taken substantially along the broken line 1-1 of Fig. 6;

Fig. 8 is a detail view of a certain valve control mechanism which functions to maintain a proper balance of oil in the oil reservoirs looking in the direction of the arrows 8 in Fig. 6;

Fig. 9 is a detail view of a shut off valve and is taken substantially along the line 9-9 of Fig. 3;

Fig. 10 is a detail view, in section, of the twoway valve assembly;

Fig. 11 is a detail view, in isometric, of one of the valve stems embodied `in the two-way valve assembly; 4

Fig. 12 is a detail view, in section, of a reducing valve assembly;

Figs. 13-15 are diagrammatic views and illustrate the machine in its respective normal, intermediate and fully actuated positions;

Fig. 16 is a diagrammatic detail view of the return valve in actuated position; and

Fig. 17 is a view, chiefly in section, of the riveting unit shown in Fig. l.

The machine is shown in Fig. 1 completely assembled and ready for operation. The riveting unit and the power generating unit are indicated generally therein by the respective numerals and 2 E. The riveting unit 2@ is connected to the power unit 2l by a plurality of pressure fluid conducting hose lines and is adapted for man-ual manipulation, independently of the power unit, anywhere within the range of the hose lines. Each unit 2U and 2l is a complete assembly in itself but is formed of several cooperating sections or ,sub-units, each detachable from the other, to facilitate assembly and replacement, or servicing. The riveting unit comprises, broadly, a handle 22, a cylinder 23, a piston assembly including a piston rod 24, and a yoke 25. The several sections of the power unit include a head 26, in which the principal control valves are mounted, an intermediate section comprising the main compression cylinder 27, and a base section 28 in which is formed the oil reservoirs, pressure outlets and `other elements and mechanisms to be described later with greater particularity. The power unit is mounted upon casters 23 to permit the unit to be moved easily Vfrom one working point to another.

In constructing this machine advantage has been taken of all known mechanical expedients to insure a maximum of efciency in its operation. In the specification, no specific mention is made ordinarily of elements such as piston rings or seals, gaskets, and the like, but it should be understood that these elements are provided in the machine, wherever necessary.

Considering rst the riveting unit 20 and referring to Fig. 17, the handle 22 is recessed to receive a pilot portion 30 integral with cylinder 23 and extending therefrom atan angle of 45 degrees relative to the axis of the main part of the cylinder. The handle 22 and cylinder 23 are secured together by means of screws 3| and are so aligned that the luidconducting passageways formed in each element are joined to form, in effect, twopassageways 32 and 33 leading respectively into the upper and lower ends of a piston chamber 34 formed in the cylinder 23. Reciprocable within the piston chamber 34 is a piston head 35 movable from end to end of the chamber under the force of oil pressure supplied alternately through the passageways 32 and 33. The piston rod 24 is secured to the piston head and extends downwardly through a bushing or cylinder extension 35 screwed into the lower end of the cylinder 23. The upper end of the extension 3B closes the lower end of the cylinder 23 to form the piston chamber 34. Packing 3l positioned within the extension 3S. about the piston rod 24, acts to prevent the seepage of oil downward between the rod and the extension. Extension 36 projects below the cylinder23 and the projecting portion thereof passes through a bore 33 formed in the upper end of the yoke 25, thus establishing a swivel connection between the extension and the yoke. In order that the yoke may be held from slipping off the. extension a split locking ring 35 is provided which ts into complementary recesses or grooves cut in the extension and yoke. The yoke 25 is normally locked against axial movement relative to the extension by an annular groove 4l in the extension cooperating with a lock plunger 42 which ts a radial bore 43 in the yoke. A screw 44, secured in the bore 43, supports a spring pressed plunger 45 which acts against the lock plunger 42 to hold it in the `annular groove 4l. Screw 44 supports a transverse pin 46 which projects through an annular recess in plunger 45 to limit its movement in both directions. A plurality of circumferentially spaced bores 4'! extend radially inward from the annular groove 4l and are arranged selectively to receive a locking plug 4B, if it is desired to inhibit swivel movement and hold the yoke 25 in a selected position of adjustment relative to cylinder 23 and handle 22.

The piston rod 24 extends through the lower end of the cylinder extension 36 and overlies an anvil head 49 formed on the yoke 25. In accordance with the usual construction of devices of this type a replaceable contact head or die 5l is positioned in the lower end of the rod 24 and a similar die 52 is positioned in the anvil head 49. It will further be noted, in connection with the piston assembly construction, that the piston rod 24 is detachably secured to the piston head 35, in order that it may be removed for individual servicing in any respect. The upper end of the piston rod 24 is formed with a head 53 which extends into a recess 54 formed in the piston head 35. A plurality of locking balls 55 are positioned below the head 53, in a groove cut in the inner wall of the piston'head 35, and normally hold the piston rod 24 with its head 53 locked within the recess 54. A removable retaining ring 56 is also positioned within the recess 54, below the locking balls 55, and serves to retain the balls in locking position.

An important, feature of the riveting unit is the ease with which it may be adapted for use in operations of varying requirements. Each of the principal elements of the unit is interchangeable with other elements of different construction and a variety of combinations of these elements may be produced. In Fig. 2, for example, o-ne of a variety of different types of yokes is shown which may be used in place of the one illustrated in Fig. 17, In Fig. 2 the anvil head 49 oi the yoke is set out of alignment with the piston rod 24, which acts thereon through an auxiliary arm 5'! pivoted on the yoke at 58 and urged into contact with the rod by a spring 53. The cylinders 23 vary chiefly in the diameter of their pressure chambers 33 and the selection of a particular cylinder is determined by the size of the rivets to be headed. The handle 22 is also replaceable and may be secured to the cylinder 23 in either of two positions, one of which is illustrated in Fig. 17, and the other in Fig. 2. In Fig. 17, the handle extends at a right angle to the cylinder and may be shifted to the Fig. 2 position merely by removing the screws 3| and reinserting them after turning the handle through an arc of 180` degrees relatively to the cylinder about the axis of pilot portion 30. It will be noted that the separate passages in the cylinder 23 and handle 22 which comprise the passageway 33 are placed in communication with each other through an annular groove 6l surrounding pilot 30 and formed by the alignment of individual recesses in the adjacent ends of the cylinder and handle. Thus,

- the handle 22 may be turned to any extent relatively to the cylinder 23 land communication between the passages comprising passageway 33 will always be maintained through the groove 6l.

Mounted within the handle 22 is the throttle control mechanism comprising a throttle valve 32 and a control lever or trigger 63 for operating the valve. The valve 62 is movable within a bushing 54, positioned within a bore 65 to which live pressure fluid such as compressed air is directed by means later to be described. The bushing 64 is open to atmosphere through a port 66 formed therein and the valve 62 controls the flow of air from the bore 65, through the bushing 64 and out the port 69. The valve 92 is urged to closed position by a spring 61 and normally prevents the escape of air from the bore 65. The throttle control trigger 63 is pivoted, at 68, to an inner surface of thehandle 22 and is formed with a shoulder 63a which engages the rearmost end of the valve 62. A clockwise movement of the trigger 63, as viewed in Fig. 1'1, serves to move the valve 62 to opened position. With the valve $2 in opened position, air is permitted to pass from the bore 65 through the bushing t4 and out the port 65 to atmosphere. This escape of pressure fluid occasions a drop in line pressure in the power generating unit which, in a manner later to be described, conditions the machine for a cycle of operation. In Fig. 11, the valve 52 and trigger 63 are shown in fully operated position,

while the normal position of the trigger is indicated in dot-dash outline.

As shown in Fig. 1, a hose line 69 is connected to the base 28 of the power unit 2l. Compressed air, generated by means not shown herein, is introduced through the hose line 69 into a chamber 1| formed in the base 28. From the chamber 1| the air passes upward through a passage 12 in cylinder casingf21 and into the head section 26 through an inlet 13 (Fig. 5) formedv therein. Inlet 13 opens into a longitudinal main air passage 14 in head 215 and extending into the main air passage is a hose coupling 15 to which is attached an intermediate thro-ttle hose 1B (Fig. 1). tends downward and into a two-way valve assembly 11, later to be described. Extending from the valve assembly 11 is a main throttle hose 18 connected to a coupling 19 (Fig. 17) which is threaded into the previously mentioned bore 65 formed in riveter handle 22. The line pressure of main air passage 14 is thus maintained, normally, also in bore 55.

Referring to Fig. 5 and the diagrammatic views, Figs. 13-15 inclusive, it will be seen that the several control valves mounted in the head 26 comprise an automatic return valve 8|, a distributing valve 82 and a preiill valve 93, so named for reasons which will hereinafter more clearly appear. These valves are movable within respective cylindrical bushings 34, 85 and 36, each of which is open at both ends in order that air may be introduced therein above and below its respective valve. Each assembly comprising a valve and valve bushing is mounted in a respective bore cut transversely through the head 26. The opposite ends of each bore are closed by closure plates t1 (Fig. 5) appropriately formed to enclose the ends of the valve bushings and to permit freedom of movement of the valves.

The valves 8|, 32 and |33 are controlled by in dividual springs and by pressure fluid supplied either directly or indirectly from air passage 14. Referring to Fig. 13, wherein the valves are shown in normal position, it will be seen that air is supplied directly to the upper end of prell valve 83 through a port 88 connecting passage 14 and a chamber 89 formed about the upper reduced portion of prefill valve bushing Sit. The valve 83 is thus normally held downward, against the tension of a spring 9|, by line pressure acting on the upper end of the valve; it being understood that expressions such as upper and downward when used in this part of the description, refer to the positions illustrated dia- As shown in Fig. 1 the hose 16 eX- grammatically in Figs. 13, 14 and 15. Air is supplied directly also to the lower end of distributing valve 82 by means of a passage 92 leading from main air passage 14 into a chamber 93 formed within the closure plate 81 which encloses this end of the valve (see Fig. 5). A downwardly eX- tending rod 94 is secured to the lower end of the valve 82 and supports a collar 95 at its lower end. Compressed between the collar 95 and an abutment 96, secured to the lower end of bushing 8'5, is a spring 91 which by reason of its arrangement urges the valve 82 downward, to the position shown in Fig. 13. Normally, line pressure is acting also on the upper end of valve 82, thereby balancing the pressure below the valve, and the spring 91 is free to hold the valve downward in the position shown in Fig. 13. If the air pressure above the valve 82 is reduced below line pressure the valve will be forced upward, against the tension of spring 91, a distance determined by the extent of the reduction of pressure above the valve. Air is directed to the upper end of distributing valve 82 through a series of ports and passageways controlled by the automatic return valve 8|. A port 9B connects the main air passage 14 to a groove 99 cut longitudinally in the outer surface of return valve bushing 84. The air passes from groove 99 through a pair of ports ||l| in the bushing 84, around a reduced portion of valve 8| and through a port |92, formed in the oppostie side of the bushing, into a second bushing groove "193. A passage |94 connects the groove |03 to a chamber |05 formed about the upper reduced portion of valve bushing 85 and thus, in the normal position of the parts, line pressure is suppled constantly to the chamber |05.

A metering orice |96 is positioned within the air passage 14 intermediate the main inlet 13 and hose coupling 15 so that the unseating of throttle control valve 62, in riveting unit 29, causes an immediate drop in pressure in the line between metering oriiice |06 and bore 65, since the air cannot pass through the orice |06 as rapidly as it escapes through port 66. The extent of pressure reduction in this line is determined by the extent of actuation given the trigger 63. Port 98 communicates with air passage 14 at a point within the area of reduced pressure so that the drop in pressure occasioned by operation of the trigger 63 is reflected also in the ports and pas-- sageways leading to chamber |05, above valve 82, and in the chamber itself.

In initiating a cycle of machine operation the trigger 93 may be fully actuated in a single motion or it may be momentarily held in a partially actuated position before completing the full stroke. Since a riveting operation consists of a first stage, in which the rivet is set, and a second stage, in which the rivet is headed, the operation of the machine will be described as consisting of separate stages, the first of which is initiated by a movement of the trigger 63 through a portion of its stroke and the second upon the completion of the trigger stroke. In Fig. 14 the machine is shown in its rst stage, or rivet setting operation, with the trigger c3 moved to an initial position intermediate its normal and fully actuated positions. As shown therein the reduction of pressure within chamber |05 has caused the valve 82 to move a short distance upward where it is held by a seco-nd compression spring I 91 placed be* tween an abutment collar |93 engaging the lower end of the valve, and the previously mentioned ,collar or spring base 95. In the normal position since no relative movement between the valve and'the collar |88 is possible until the collar engages the abutment S8. This occurs upon completion of the initial upward movement of the valve 82 and it will beevident that further upward movement of the valve must be accomplished against the combined action of springs 91 and |81. With the valve 82 in the intermediate position shown in Fig. 14 the live air acting upon the lower end of the valve is permitted to pass through a port |59 in abutment collar 88, around the reduced lower end of the valve and through a pair of ports HI into an annular groove H2 formed in the outer surface of the bushing 85. lA

passageway 3 leads from the groove 2 to a chamber |13 formed around the reduced lower end of preiill valve bushing 88 so that upon the initial movement of distributing valve 82 line pressure is established in chamber H41. Extending from the chamber ill is a passageway H5 which leads downward through the intermediate section of the unit to the base and opens into a prell reservoir lili containing a suitable liquid, such as oil. Live air pressure acting upon the oil in reservoir |95 forces the oil through a passageway ||1 into a pressure chamber ||8 and thence through means, including a hose line HS, t handle 22 of riveting unit 28. In handle 22 the oil is driven through the passageway 32 and into the upper end of piston chamber 35|, forcing .piston head 35 and rod 28 downward to set the rivet. The hydraulic system is actuated at this time solely by air pressure within the reservoir HB so that the pressure obtained in pressure chamber 31| is relatively small and insufficient to actually head the rivet.

Returning now to a consideration oi the prerlll valve 83 it will be observed that while air is passing from chamber H4 down to the reservoir ||6,. air is also seeping slowly between the inner edges of bushing 88 and a projection |21 of slightly less diameter than that represented by the inner edges of the bushing. Thus, while the rivet setting operation is in progress, pressure gradually builds up below the prell valve 83 and, as the gradually increasing pressure counterbalances the line pressure acting on top of the valve, the spring 9| moves the valve upward. The upward movement of the valve 83 is further retarded by reason of the fact that the air, above the valve, can escape only through a narrow opening between the upper end of the valve bushing and the closure plate 81, similar to the opening between the lower end of the jection 52|. The valve S3 is shown in Fig. 14 in an intermediate position with its upper end still closing a pair of ports |22 communicating with the Lipper chamber S9 which receives line pressure through port 88 directly from the main air passage 14. When the prell valve has moved upward a slightly further distance it will uncover the ports |22, allowing air to flow through the ports around a reduced portion of the valve and through another pair of ports |23 into an annular groove |24 formed in the bushing 8B. The groove |28 is connected, by means of a passage |25, to an annular groove |28`formed in the distributing valve bushing 85. The groove |26 communicates with the interior of the bushing B through a set of po-rts |21 which are closed by the head of the distributing Valve in its normal and intermediate positions.

When operating thecontrol trigger 63 in two steps the second step, to fully actuated position,J

bushing and proof rthe valve '82 the .spring |81is withouteiiect is performed after the rivet setting stage of the operation and may take place before or after the ports |22 are uncovered by the preiill valve. In Fig. l5, the trigger 63 is shown fully actuated and the throttle control valve 62 completely open. The drop in pressure between the riveting unit and the metering oriiice |86 is considerable, at this time, and, as reflected in chamber |05 above the distributing valve 82, is suiiicient to permit the valve 82 to be moved to its extreme upward position against the tension of the two springs 91 and |01. This movement of the valve 82 from its Fig. 14 position to its Fig. 15 position serves to uncover the ports |21 and permit air to flow through the ports around a reduced portion of the valve and through a second set of ports |28 into another annular groove |29, formed in the bushing 85. Communicating with the groove |29 is a passageway |3I which extends downward and opens into a main compression chamber |32 containing a piston assembly including a piston head |33 and rod |34. Normally, and during the rivet setting stage of operation, the piston assembly in chamber |32 occupies the position shown in Figs. 13 and 14. However, upon the extreme upward movement of the distributing valve, line pressure passing through the above described ports and passageways enters the upper end of chamber 32 and drives the lpiston assembly downward, as is illustrated in Fig. 15. Piston rod |34 extends downward into the oil pressure chamber ||8 and, in moving through the chamber, forces oil at great pressure through the passageways leading into riveting piston chamber 34 to drive the riveting piston assembly downward and complete the rivet heading operation. If, for any reason, it should be desired to prolong the rivet heading operation .beyond the normal time in which this operation is performed a means is provided for reducing the iiow of air to the chamber |32 to increase the time required to build up sufficient pressure therein to operate the piston assembly. This means resides in a set screw |38 adapted to engage the upper end of the prell valve 83 to limit the upward movement of the valve. As shown in Fig. 5, the screw |38 extends through the plate 81 enclosing the upper end of prell valve bushing 85 and may be manually set to any desired position of adjustment. When the valve 83 is prevented from completing its upward movement, the ports |22, controlled by the valve, are only partially opened andthe ilow of air through the ports is accordingly reduced.

The rivet heading operation being now complete, the trigger 63 may be released. Upon release of the trigger, the air in the passageway 18 between the riveting unit and the metering orice |88 will build up to line pressure and this pressure can be used to return the distributing valve 82 to its normal position, thereby cutting off the flow of air to the main compression chamber |32 and prellreservoir H6. However, an automatic control means, which acts independently of the trigger 63, is provided for returning the valve 82 when a predetermined point of peak pressure is reached in the chamber |32. 'Referring to Fig. 15, a second passageway |35 opens into the upper end of the chamber |32 and eX- tends upward into a bore |38 formed in the head 28. Positioned within the bore |38 is a valve |31 which normally closes the passageway |35 and is urged to closed position by a spring |38. An adjusting screw |38 also extends into the bore |38l and acts upon the spring |38 to increase or lessen the pressure with which it urges the valve |31 to closed position. Thus, when the pressure in chamber |32 reaches a sufliciently high point to force valve |31 off its seat, air is permitted to pass from the chamber into the bore |36 and from there through a passage |4| into a chamber |42 below the automatic return valve 8|. The pressure fluid thus introduced into chamber |42 immediately forces the valve8| upwards, against the tension of a spring |43, into the position shown in Fig. 16. As shown in the latter figure, the valve, when in its upper position, closes the port |82, leading into groove |63, but establishes communication between this groove and the interior of the bushing 84 through another port |44. Also formed in the bushing 84, opposite the port |44 and opened by upward movement of the valve, is a port |45 communicating with a passageway |46 leading directly from the main air passage 14. The passageway |46 opens into the main air passage at a point between the air inlet 13 and metering orifice |56 so that full line pressure may pass through passageway |46 and port |45 around a lower reduced portion of valve 8| and then through port |44 into groove |63. From groove|63 the air flows, of course, through passage |64 into chamber |95 above the distributing valve 82, forcing this valve downward to the normal position of Fig. 13 and thereby closing ports |21 and to stop the flow of pressure fluid to chambers |32 and ||6 respectively.

Still referring to Fig. 16, it will be seen that the air of reduced pressure below the metering orice |86 flows from groove 98 in bushing 84 through the upper one of the ports lui, around the upper reduced portion of the valve 8| and then through a passage |41, formed in the bushing, into a chamber |48 above the valve. As the air in chamber |48 builds up to a sufficient pressure to balance the pressure acting upon the `lower end of the valve, the spring |43 returns the valve downward to its normal position. This occurs upon the closing of the throttle valve 62.

In order to speed up the return action of the valve 8|, an auxiliary return connection may be provided. The bushing 84 is formed with a port |49, normally closed by the valve 8|, communicating with a passage 15| leading into an opening |52 (Fig. 5) from which extends another passage |53 opening into the main air passage 14 below the metering orifice |86. Upon movement of the valve 8|, the lower reduced portion thereof is placed opposite the port |49 and line pressure passing around this reduced portion from port |45 is admitted through the port |49 to passages |5| and |53. A metering orice |54 is positioned in the opening |52 (Fig. and delivers, at a restricted rate, compressed air into passage |53 and hose 18, thereby complementing the action of orifice |86.

1t is also desirable, for quick and efficient operation of the machine, that the relief valve |31 be returned to its seat immediately after it has performed the function of causing the operation of valve 8| to the Fig. 16 position. To insure prompt A the relief valve, and chamber |42, below the `end of the valve.

valve 8|, is positively cut off from the chamber |32.

In order that the Valve 8| may be retained in its upper, or actuated position, for the time necessary to accomplish the return of the distributing valve 82, a small opening |51 is formed in the lower reduced portion of the valve 8| which communicates with a bore |58 drilled in the lower Pressure fluid from port |45 thus passes also through the opening |51 and bore |58 into the chamber |42 and acts upon the lower end of the valve 8|. After the closing of relief valve |31 air 'is supplied to the chamber |42 only through the opening |51.

If, and as long as, the operator, subsequent to the completion of the rivet heading stroke of pistons |33 and 35, continues to hold the throttle valve 62 open, the automatic return valve 8| will be held in its upper or operated position illustrated in Fig. 16 by the preponderance of the pressure of substantially live air, delivered through opening |51 and bore |58, over the opposing combined pressures of spring |43 and fluid under reduced pressure. Under these conditions such reduced pressure, in hose 18 and associated passages, does not initiate a new cycle of operation as before, because the automatic return valve 8| is now positioned to deliver live air through passage |84 to the upper end of distributing valve 82. Upon release of throttle valve 62 to closed position, air pressure in hose 18 builds up to line pressure to balance the fluid pressures at the ends of valve 8| and permits the spring |43 to restore it to the normal (Fig. 13) position. The auxiliary passage |53, associated with metering orifice |54, performs an important, though not indispensable, function in augmenting the rise in pressure in hose 18 with the consequent restoration of valve 8| to normal, following the close of throttle valve 62. The operator, therefore, may reopen the throttle valve to head4 a new rivet without any appreciable delay on account of the'restoration of valve 8| subsequent to the closing of the throttle valve.

The return stroke of the main driving piston |33|34 begins immediately upon the return of the distributing valve 82 to normal. Since the driving piston encounters less resistance on its return than on its power stroke, reduced pressure may be used for its return, thereby effecting a saving in compressed air. As shown in Fig. 13, in the normal position ofthe valve 82 air, at line pressure, flows through a branch |58 of the passageway 92 into an annular groove |6| in distributing valve bushing 85. From groove I6 I', the air passes through a set of ports |62, around a reduced portion of the valve 82 and out a set of ports |63 into a second annular groove |64. A downwardly extending passageway |65 communi- Cates with the groove |64 and a branch |66 of the passageway leads into a bore |61 formed in a projecting portion |66 of the cylinder 21 (see Figs. 3 and 12). Positioned within the bore |61 is a well-known type of` reducing valve assembly |68, having a valve |69 movable within a bushing |1| to control the flow of air into passage |12. An adjustable spring |13 presses upon the lower surface of a diaphragm |14 to urge the Valve |69 to open position while air entering the open upper end of bushing |1| acts upon the upper end of the valve to close it when the diaphragm is forced downward. The air iiows'into the upper end of bore |61, through a set of ports |16, in the bushing |11, and past the valve |69 to the passage |12 where it is directed to the lower end of bore l|61 and -out a passage |11. In passing from passage |12 to passage |11 the air acts on the upper surface of the diaphragm |14 and presses it downward against the tension of spring |13. The valve |69 is thusV allowed to move downward to a partly closed position and, as a result, the pressure of the air passing from thel lower' end of bore l61 is substantially less than that of the air entering the upper end of the bore. The passage |11 opens into the lower end of com'- pression chamber |32, below the piston head |33, and the air of reduced pressure thus introduced below the piston head serves to return the piston to its normal upper position.

Provision is made for directing air, trapped on either side of the piston head |33, to exhaust. Referring to Fig. 1,3, it will be seenthat during the upward travel of the piston 13B-|34, the air above the piston isl forced out of the chamber through the passageway |3| and enters groove 29. From groove |29 the air passes through ports Y|28 aroundv the upper reduced portion of valve 82 and out a pair of ports |18 into an annular groove |19 formed in the bushing 85. Communicating with groove |19 is a passageway |8| leading, in a manner not shown herein, to, an exhaust chamber |82 (see Figs. 6 and '1.) formed in the base 28. Extending into the chamber |82, through an opening in the Ybase plate |80, is a muffler comprising a perforated retainer |83 lled with copper wool or a like substance. A closure plate |84 covers the lower end of the reT tainer |83 and exhaust air is permitted to pass through the retainer and out openings |85 in the plate |84, to atmosphere. During the downward movement of the piston ISS-|34, the distributing valve 82 is in its uppermost po-sition and, as shown in Fig. 15, the exhaust port y|18 is, at this time, opposite a lower reduced portion of the valve and is thus in .communication with the ports and passageways leading into the lower end of compression chamber |32. During this portion of the cycle, therefore, the air' below the piston head |33 is driven to the exhaust chambel' 82,v ia passages |11, |66, |65, etc.

It Vis also desirable that chamber I |4, below the prei-lll valve 8,3, be connected to exhaust in the normal position .pf the machine in order that the .oil in reservoir I6 may return to its normal level. Thereforaan opening |86 is formed in a grooved portion of the distributing valve 82 and communicating with the opening is a longitudinal bore |81 in the valve. In the normal position of the valve 82 (Fig. 1,3) the opening |86 therein lies opposite ay pair of ports |88, in the bushing 85, which communicate with the previously mentioned annular groove ||2. Exhaust air is then free to ow from chamber ||4 through the connecting ports andv passageways to opening |86 and then through longitudinal bore |81. At the upper end of bore |81, another opening |89 is formed in the valve 82 and the air from bore |81 passes out this opening, around the upper reduced portion of the valve and out the exhaust port |18.

Turning now to a further consideration of the hydraulic system it will be remembered that the initial movement of the oil takes place during the first or rivet setting stage of the cycle, when live air-under the usual line pressure, say, 90 pounds per square inch, is admitted to the preflll reservoir ||6. Then, during the second or rivet heading stage of the cycle, the main driving piston |33| 34 is actuated and the oil ahead of the drivingpiston. forces the riveting piston assembly downward substantially to its Fig. l5 position, with a pressure of several tons. In order that the riveting piston may be retuined to its normal position after each rivet heading operation, oil is supplied through passageway 33, in the riveting unit, to the lower end ofnthe pressure chamber 34 below the piston head 35. Referring to Figs. 13-15, there is provided in the base section 28 of the power unit, a return oil reservoir |9| into the upper end of which opens the passageway |85. In the normal position of the distributing valve 82 (Fig. 13) air under line pressure ows through this passageway and thence through parallel branches to serve the dual purpose of returning the driving piston |33|34 and acting upon the oil in reservoir |9| to effect the return of the riveting piston. Reservoir |9| is in communication with an oil pressure chamber |92 in which is mounted a return piston |93. Upon the introduction of 'live air into the reservoir 19| the oil therein is forced downward into the pressure chamber |92 where it acts upon the base of the piston |93 to force it upwards. As the piston |93 moves upward oil above it is forced through means including a hose line |94 to the riveting handle 22 where itis conducted by means oi passageway 33 tothe pressure chamber 34 where it returns the piston assembly therein to the normal position yof Fig. 13. It will be recalled that upon the first step (Fig. 14) of the distributing valve 82 to actuated position the ports |82, by which live air is conducted to the passageway |65, are closed and line pressure is hence cut off from the reservoir |9|. Further, the passageway |35 is opened to exhaust at this time so that no air pressure opposes the riveting piston as it descends toits rivet setting and rivet heading positions. On the return stroke of the piston head 35 the oil above it retraces its path through passageway 32, hose H9, and back to the prell reservoir H8, which is open to exhaust at this time through chamber I4, below prell valve 83. On the actuating stroke of piston head 35, the oil below it passes back through passageway 33, hose |98, and on to pressure chamber |92 where it assists in moving the piston |93 downward to the position shown in Fig. 14. The primary force in lowering the piston |93 is oil from the prei-lll reservoir l IB,

introduced through a connecting passageway |95Y which opens into the pressure chamber |92 at a point above the head of the piston.

In order that a proper balance of oil may be maintained in the various sections of the hydralic system certain valvular control mechanisms are provided. As shown in Figs. 3 and 6, the return reservoir |9| and pressure chamber |92 are separated by a wall of the base casting, which does not, however, quite reach the base plate |88 and so permits constant communication between the lower end of the reservoir and the lower end of the chamber. Referring particularly to Fig. 3, the piston |93 is formed with a bore |91 which extends throughout the length of the piston and communicates, through a pair of ports |98, with `the lower end of chamber |92 below the head of the piston. Supported within the bore |91 is a bushing |99 in which is mounted a valve 28 l. The valve 28| is movable within the bushing |99 to open and close a pair ofv ports 292 by which communicaticn is established between the bore |91 and the upper end of chamber |92 above the piston |93. The valve 28| is urged .to closed position by a compression spring 283 extending between a shoulder of bushing |99 and an abutment collar 204 secured to the lower end of the valve, but, in

the operated or downward position of the piston, the valve is held in open position by reason of the engagement of collar 269 with base plate |86. The operated position of the assembly is shown in Fig. 3 and it will be seen that, at this time, oil may pass from the upper end of the chamber |92, downward through the ports 292 into the bore |91 and out the port |98 to the lower end of the chamber |92 and to the reservoir |9I. Then, when compressed air is admitted to the reservoir |9| to initiate a return stroke of the Iriveting piston, oil passes from the reservoir through the ponts |98 into the bore |91 and `out the ports 292 to the upper end of the chamber |92. When the upper end of the chamber is filled, the oil from the reservoir |9| acts upon the lower surface of the head of piston |93 and forces the piston upward. Upon the initial upward movement of the piston, the upper end of bushing |99 engages the head of valve 26|, thus closing the ports 262, and during the subsequent upward movement of the piston the several elements |93, |99 and 26| move tocontrol the flow of oil through a narrow opening 2|3 in the block. The valves 2|| and 2|2 are spaced slightly from the inner guide walls of the blockv 299 to permit the oil to pass. around the valves to the opening 2 3. The valve 2 I2 is urged upward to closed position by a spring 2|4 and is formed with a stem or` extension 2|5 which passes through the opening 2 |3 and underlies the lower end of valve 2| l. With valve 2|2 in upper or closed position the extension 2|5 thereof engages the valve 2|| and holds it oi its seat, in open position. As shown in `Fig. 8 the midportions of the valve 2 I2 and block 209 are slotted vertically to permit the passage of oil to and from the valve and to receiveone end of a lever 2 I5 pivoted, at 2H, to an inner wall of the block.

gether as a unit and the valve remains in closed position. The oil above the piston |93 is forced out a passageway 205 which opens into the upper end of chamber |92 and connects, in a manner not shown herein, to the return oil hose |94 (Fig. 1).

In the present hydraulic system, as in those of a similar class, a certain amount of oil seepage takes placeabout the piston head 35 in the chamber 39. In general, the seepage in one direction past the piston is counteracted by seepage in the opposite direction during a different part of the cycle but, as a practical matter, real equality of balance is rarely if ever attained. Thus, in the present instance, the amount of oil which seeps from the upper end of chamber 34 to itslower end during extended operation of the machine exceeds by a considerable amount of seepage which takes place during the same period in the opposite direction. Also, if the machine stands idle for a protracted period, with the air pressure turned on, oil will pass from the lower end of chamber 34 to the rupper end and none at all return in the opposite direction. Excessive seepage in either direction past the piston head 35 will cause a variation in the normal level of the oil within return reservoir |9I. Should this level go too high the oil may overflow into the air passages and if the level goes too low the supply therein may be insuicient to operate the return piston |93. Wide variations of the oil level in reservoir |9| are, therefore, undesirable and, in order to confine variations within narrow limits certain additional control mechanism is provided. As shown in Figs. 6, 'l and 8 the return reservoir |9| and the prell reservoir ||6 are connected by a pair of passageways 266 and 291, the latter of which is in communication with a bore 268 (Fig. 7) opening into the reservoir E9 The passageway 201 communicates also with the pressure chamber |92 (see Figs. 3 and 6) at a point above the head of piston |93, so that, during the prell operation, oil passes from the reservoir i6 through the passageways 206 and 29'! and acts to return the piston |93 downward. The previously mentioned passageway |95, shown in Figs. 13, 14 and 15, is a diagrammatic representation of the connection, effected by passageways 206 and 291, between the reservoir I6 and chamber |92.

Positioned within the bore 268 (Figs. '7 and 8) and extending below itinto the reservoir |9| is a block 299 which acts as a bushing for a pair of oppositely disposed valves 2|| and 2|2 which The lever 2 I6 bears, at its left hand end, as viewed in Fig. 8, a laterally extending stud 2| 8 which passes through an opening 2|9 in the valve 2|2 and projects into a horizontal slot 22| formed in the block 299. The valve 2|2 may thus be raised and lowered by operation of the lever 2|6 which is movable about its pivot point 2|? a distance limited to the range of movement permitted the stud 2|8 by the opposite edges of the slot 22 .Y The right hand end of the lever 2|6, as viewed in Fig. 8, is pivotally connected to a rod 222 secured to the lower one of a pair of connected buoyant elements 223 which float on the surface of the oil in reservoir |9|. The rise and fall of the oil in this reservoir is reflected, therefore, in a corresponding movement of the lever 2|6 and a consequent downward or upward movement of the valve 2|2. When the oil level in reservoir |9l rises suiciently to cause the opening of valve 2|2 oil may pass from the reservoir, through the opening 2|3 past valve 2|I and through thepassages 291 and 296 to the prell reservoir |6. As the oil level drops in reser- Voir |9| the `lever 256 is caused to move in a clockwise direction (Fig. 8) and lift valve 2|2 to closed position in which position, theV extension 2|5 thereof may lift valve 2| off its seat to permit oil from the prefill reservoir to pass downward through the opening 2|?. and around valve 2|2 into the return reservoir. In order that the valve 2|2 may be partly unseated at this time, it is permitted a slight movement relatively to the lever 2|6. It will be noted that the opening 2|9 in the valve, through which the stud 2 |8 is passed, is of slightly greater diameter than the stud The valve 2|2 is held in its fully closed position by the spring 2M while the stud 2| 8" is held a short distance below the upper edge of the openf ing 2|9 by reason of its engagement with the upper edge of the slot 22|. Thus the valve 2|2 may be moved downward a distance suicient to permit oil to iiow downward through the opening 2|3, even though the lever 2 I6 and buoyant elements 223 be in their lowermost positions. The relative movement of the valve 2|2, at this time, is not enough to permit the valve 2| l to return to its seat. Valve 2| will close only when the buoyant elements 223 rise and pull valve 2 2 a further distance off its seat. The exchange of oil between the prefill reservoir and the return reservoir takes place when compressed air is admitted to these respective chambers, and it will be noted that, by reason of the construction of the valves 2|| and 2|2, an exchange of oil will take place during each cycle of machine operation. The valves 2| and 2 I2 cannot occupy their seats at the same time and it is always possible to force oil in one direction or the other through the opening 2|3,

When live air is admitted to prefill reservoir H6 during the rivet setting portion of the cycle, oil is forced past the valves 2'|| and 2'|2 until the oil level in the return reservoir rises to a point where valve 2 2 will be pulled fully oi its seat and valve 2|| permitted to drop to closed position. Then when air under pressure is admitted to the return reservoir |9|, during the piston return or normalizing portion of the cycle, oil is forced past the valves 2|2 and 2|| into the prell reservoir until the oil level in the return reservoir drops suiiciently to permit valve2|2 to move to fully closed position. If there is an excessive amount of oil in the return reservoir, the valve 2|2 remains open for a period longer than normal If there is a lack of oil in the return reservoir, a correspondingly longer time is required to pull valve 2| 2 off its seat, during-the rivet setting stroke, and additional oil may iiow from the preflll reservoir past the open valve 2| As pointed out in the description of the riveting unit 25 the several sections of this unit are interchangeable and the unit may easily be adapted to meet the requirements of any particular riveting work. Occasionally, however, a class of work is4 encountered which requires frequent changes from one type of riveting unit to another. In such instances, the more practical manner of working is to provide a plurality of riveting units, each differently arranged, and to select one or another for use, as the work shall require. In order to simplify this manner of working the present power generating unit is so constructed as to permit the attachment thereto of two riveting units, and a manually controlled two way valve assembly is provided whereby the units may be alternatively conditioned for operation.

The two way valve assembly has been previously identied as a unit by the reference numeral ll (Fig. l) and is comprised in a projecting portion 224 of the base casting, a valve chamber 225, above the portion 224, and an intermediate guide `block 226 positioned between the elements 224 and 2,25 and secured thereto. The assembly is shown in section inFig. 10 and, as shown therein, the chamber 225 is formed with an air inlet 221 to which air, at reduced pressure, is conducted from the main air passage below metering orifices |06 and 54 through the intermediate throttle hose 15. Also formed in the chamber 225 is a pair of air outlets 228 'and 229, each of which receives one end of a respective main throttle hose 78. The projecting portion 221i is formedwith a high pressure Aoil passageway 2M' and a pair of outlets 232 and 233 each of which receives one end of a respective oil hose its. The machine illustrated in Fig. l has only one riveting unit attached thereto but it will be evident that additional hose lines 'i8 and |59 can be readily attached to the respective outlets 229 and 233. A second return oil hose '|82 must also be used with the second riveting unit and there is accordingly provided, as shown in Fig. 3, a second outlet 295 in communication with the chamber |82. When only one riveting unit is attached to the machine, the second outlet 295 must be closed by a suitable plug. Returning now to a consideration of the valve mechanism shown in Fig. l0, there is positioned within the chamber 225 a valve 234, and within the projecting portion 224 a valve 235. The valves E34 and 235 are rotatable within respective bores and associated with each valve is a respective valve stem 23S or 23T: positioned within the intermediate guide blocki 226.

Each of the stems 236 and 231 is formed, at one end. with projecting lugs 238 (see Fig. 11) adapted to nt into correspondingly shaped recesses cut in the adjacent end of its associated valve. The opposite end of each stem is cut away to form a generally rectangular portion 239 which extends into a correspondingly shaped slotcut in the inner end of a lever 2M which extends outside the guide block 226 and is accessible for manual operation. The valves 234 and 235, the stems 235and 237, and the operating lever 25| are thus intertting and are rotatable as a unit. The valve 234 is formed with a longitudinal passage 222, near its upper end, and with a similar passage 2.43, near its lower end, positioned at right angles to the vertical plane of the .upper passage. Formed in the chamber 225 on opposite sides of the valve 234, adjacent the passage 222, is a port 2M communicating with the outlet 2253 and a port 265 communicating with a passageway 26E-G leading to the air inlet 227. Similar ports 24T and 228 are formed on opposite sides of the valve 234, adjacent the passage 2153, these ports leading respectively to the outlet 229 and the passageway 226. It will be evident that by rotation of the valve 234 degrees in opposite directions communication may be established alternatively between the passageway 246 and the outlets 228 and 229.

A generally similar arrangement of ports and passageways is used to direct oil alternatively to the outlets 232 and 233 in the projecting portion 2251. In this instance, however, oil passes directly from passageway 23E through a passage 249 in the valve 235 to the -outlet 232, but passes indirectly to outlet 233 through upper and lower openings 25| and 252 which are connected by a longitudinal passage 253 formed in the valve. The operating lever 24| is movable to two different positions to rotate the valves 234 and 235 and the valves are so arranged that in one position of the lever air is directed to outlet and oil to outlet 232, while in the other position of the lever air is directed to outlet 229 and oil to outlet 233. In order that the valves 231| and 235 may be maintained in a proper vertical position with respect to the ports and passageways which they control, a compression spring 251i is interposed between each valve and the adjacent end of its associated stem.

The means for directing high pressure oil to the two way valve assembly has not yet been fully described. As shown in Fig. 3 the passageway 23| which extends into the projecting portion 224 opens, at its other end, directly into the mid-portion or the pressure chamber H8 through which the piston rod 634 reciprocates. Gil from the preill reservoir H5 is introduced into the chamber |58 through the passage which communicates, through a longitudinal passage 255, with a recessed portion 255 of the chamber l i8. Fixed within the chamber H8 is a bushing 25'! which covers the recess 256 and extends downward to a point just above the passageway 2.3i'. A pair of ports 258 are formed in the bushing 25'! adjacent the recess 256. In the normal position of the driving piston |3'3-l3'4, the lower end of the rod |34 lies within the upper end of the bushing 25l just above the ports 253. Thus when compressed air enters the reservoir i l5 the oil is permitted to pass through the ports 253 into the chamber H8, and a like amount of the oil is driven out the passageway 231' to complete the rivet setting operation. Subsequently, the piston rod |34 moves down- |32 may be varied by operation of the adjusting screw |39 (Figs. 13-16) to vary the pressure with which the relief valve |31 is urged to closed position. It is desirable to vary the peak pressure obtainable in the chamber |32 since, by this means, each riveting operation may be performed with a maximum of efficiency. In heading rivets of different size the screw |39 is set in accordance with the size of the rivet to raise or lower, the air pressure within the chamber |32. It will be evident that by reason of this adjustable means a considerable saving of time and compressed air is effected. To `assist the operator in determining the proper setting of the screw |39 for each size rivet a standard pressure gauge, which may be caused to register the degree of pressure Within the chamber |32, is axed to the machine. Referring to Figs. `4 and 5, the pressure gauge is indicated at 259 and has the usual stem 26| which is actuated to obtain the reading. The gauge 259 is threaded into a projecting portion of the closure plate 61 enclosing the lower end of the prell valve bushing 86 and communicates indirectly with the main compression` chamber |32. A passageway 262 yleads in a manner not'` herein shown to the chamber |32 and opens into a bore 263 formed in the projecting portion of the above-mentioned closure plate 61. A passage 264 (Fig. 4) connects a reduced portion of the bore 263 to the gauge 259, and a manually operable plunger valve 266 is positioned in the reduced portion of the bore for controlling the ow of air to the passage 264. By reason of the valve 266, the gauge 259 is normally cut off from communication with the chamber |32 and when it is desired to ascertain the pressure within the chamber, the valve 266 is actuated and the operating trigger 63 compressed to initiate a cycle of operation.

One of the remaining structural features to be considered is a pair of shut off valves 265 and 266 (Fig. 3) positioned in the'respective passageways |65 and ||5. The passageways |65 and ||5 conduct air to the respective reservoirs |9| and ||6 and the valves 265 and 266 are provided in order that these passageways may be closed, when transporting the machine, to prevent oil from flowing into the head of the machine. The valves 265 and 266 are similar in construction and operation, and only the valve 265 is shown in detail herein.` As shown in Fig. 9 the valve 265 is posi-^ tioned in a bore 261 which connects separate.

portions of the passageway |65 an-d branch |66 thereof. The valve is adapted to be moved manenter the air passages. As shown in Fig. 3, each baie plate comprises a pair of discs 266 and 269 spaced apart and held in a xed position by a screw 21| which extends through the upper end of the base casting. The two bale assemblies are identical and a description of the one positioned in reservoir |9| will suffice for both. The upper disc 268 is perforated and abuts against shoulders formed in the casting to create a chamber 212 in the upper end of the reservoir. The lower' end of the .passageway |65 opens into the chamber 212 and the air discharged therefrom passes through the perforations in'disc 268 and is so deflected by the lower disc 266 as to exert a substantially even pressure on the entire surface of the oil.. y

A collection of air in certain sections of the hydraulic system is unavoidable. 1n the riveting unit, when one cylinder 23 is replaced by another,

air is trapped in the cylinder and connecting oil passages. In the power generating unit, air from the compression chamber |32 gradually accumulates in the oil pressure chamber ||8 and connecting passageways. A simple but effective method has been devised for removing the air trapped in these sections of the hydraulic sysually through the bore 261 to close the portion of passageway |65 which extends downward to the return reservoir |9|.

As a further means of controlling communication between the reservoirs I6 and 9I and their respective passageways ||5 and |65, a baflie plate is provided in each reservoir in order that air from the passageways will not churn up the oil to'such an extent as to create a mist which might tem. Considering first the riveting unit and re-' ferring to Fig. 1'1, the cylinder 23 is formed with an opening 213 which opens directly into the upper end of the chamber 34 and with an opening 214 which opens into the lower end of return oil passageway 33. The openings 213 and 214 are closed by respective plugs 215 and 216. To remove the air trapped in cylinder 23 above the piston 35, the plug 215 is loosened suniciently to allow air to escape slowly along the threads thereof. Then, with the unit suspended in the position shown in Fig. 17, the trigger 63 is compressed to an intermediate position and the oil which is thus caused to ow through the passageway 32 and into the upper end of the chamber 34 forces the' air out the opening 213. When oil appears through the threads of the plug 215 the plug isl again tightened. To remove the air trapped in the cylinder 23 below the piston 35, the unit should be held in a position inverted from that shown in Fig. 17. The plug 216 is then loosened and, with all valves in normal position, return pressure oil entering the cylinder through passageway 33 will force the trapped air out the opening 214. v

Air is forced from the pressure chamber H8 through the previously mentioned passage 255 (Fig. 3) one end of which communicates with the upper end of chamber ||8 and the other end of which may open through the base casting to atmosphere.v The outer end of the passage 255 is normally closed by a plug` 211. A iillei` port 218, through which oil is supplied to the prell reservoir ||6, is provided and it will be noted that the upper end of the ller port lies,k

" ting threads `of the plug.211. When oil appears along the threads, .the plug is tightened.

'- In accordance with the usual construction of machines of this general class, an air line oiler of any suitable type may be lprovided in order that a small amount of oil may be introduced into the live air as a lubricant for the valves and air operated pistons.

While the invention has been described with particular reference to a compression riveter, it is susceptible of embodiment in riveters of the type Which loperate with a pulling action.

The riveting tool illustrated in Fig. 17, which includes an `adjustable kyoke and an adjustable handle arrangement, is claimed in a divisional application filed April 10, 1943, by Howard R. Fischer, Serial No. 482,575.

The tank level control apparatus, shown best in Figs. 7 and 8 hereof, forms the subject matter of another divisional application, Serial No. 559,- '762, filed by applicants on October 2.1, 1944.

What is claimed is:

1. In apparatus for riveting or the like, the

combination of a plurality of pressure iiuid operated riveting units, a source of pressure fluid common to all of said riveting units, and settable means intermediate said source of pressure iiuid and said rivetingl units for directing pressure fluid selectively to said riveting units'. 2. In apparatus for riveting or the like, the combination of a plurality of riveting units each having a throttle control mechanism and a piston chamber, a source of pressure fluid common to all of said throttle control mechanisms, a source of pressure fluid common to all of said piston chambers, a settable means intermediate the first said pressure fluid source and said throttle control mechanisms for directing pressure fluid selectively to said throttle control mechanisms, a settable means intermediate the second said pressure fluid source and said piston cham'- bers for directing pressure uid selectively to said piston chambers, and a single means for operating the tvvo said settable means.

3. A unit for performing compression riveting and like operations, comprising a cylinder, a pressure fluid operated piston reciprocable in said cylinder, twopressure fluid conducting hose lines connected to the cylinder and supplying fluid respectively .to the front and rear ends thereof, a third pressure fluid conducting hose line connected to said unit, means on the unit for exhausting the fluid from the third said hose line to initiate by remote control the flow of iiuid through the iirst and second said hose lines, and

intensifier means for abruptly increasing the pressure of the uid supplied to the cylinder and being automaticallyoperable upon an increase in the rate of exhaust from said third hose line. 4. A unit for performing compression riveting and like operations, comprising a cylinder, ar

pressure iluid operated piston reciprocable in `said cylinder, two pressure fluid conducting hose lines connected to the cylinder and supplying uid respectively to the front and rear ends thereof,`

a third pressure fluid conducting line connected to said unit, means for initiating operations by communicating said thirdline to exhaust, means on the unit for regulating the rate of flow to exhaust, and automatic means for intensifying the pressure in one of said hose lines upon an increase in the rate of oW to exhaust.

5. A fluid actuated riveting'mechanism adapted to be manually carried and manipulated and includingl a iiuid pressure responsive piston, a first uid conducting line connected to the mechanism and arranged to deliver liquid under pressure to one side of the piston, a second iiuid conducting line connected tothe mechanism and arranged to deliver liquid under pressure to the opposite side of the piston, a third fluid conduct` ing line connected to `the mechanism and arranged to deliver compressed air thereto, means responsive to variations in the air pressure Within said third line for controlling the application of liquid pressure through said first and second lines, manipulative means on the mechanism for communicating said third line to exhaust and regulating the rate of now to exhaust, and automatic means for intensifying the pressure in said nrst fluid conducting line upon an increase in the rate of iow to exhaust.

6. A compression riveter completing a .rivet installation in separate setting and heading stages of operation, comprising a iiuid pressure responsive piston in the riveter, a fluid conducting line connected to said riveter and arranged to deliver pressure iiuid to said piston in a direction to set and head the rivet, -means for controlling the application of pressure through said line, said means having off-normal positions occupied respectively during the' rivet setting and rivet heading stages of operation, and means on the riveter operable in a step-by-'step fashion to l initiate movement of said control means from a normal to an oli-normal position and from one off-normal position to another.

7. A compression riveter completing a rivet installation in separate setting and heading stages of operation, comprising a fluid pressure responsive piston in the riveter, a rst fluid conducting line connected to said riveter and arranged to deliver liquid pressure 'to said piston in a direction to set and head the rivet, a second fluid conducting line connected to said riveter and delivering compressed air thereto, means responsive to variations in the air pressure within said second line for controlling the application of liquid pressure through said first line, said means having off-normal positions occupied respectively during the rivet setting and rivet heading stages of operation, manipulative means on the riveter settable from an olf position to intermediate and on positions for communicating said second line to exhaust and regulating the rate of flow of the escaping fluid, and automatic means for intensifying the pressure in said first fluid conducting line upon an increase in the rate of Yilovv of the escaping fluid 4 8. A compression riveter completing a rivet installation in separate setting and heading stages of operation, comprising a` fluid pressure responsive piston in the riveter, a uid conducting line connected to said riveter and arranged i to deliver pressure fluid to said piston in a direction to set and head the rivet, another fluid conducting line connected to said riveter and arranged to deliver fluid to said piston in a direction to .return it from a rivet heading operation,

means for controlling the application of pressure through said lines, said means having a normal position in which the first said line is open to exhaust and being movable to an intermediate and a fully actuated position occupied respectively during the rivet setting and rivet heading stages of operation and in each of which the second said line is open to exhaust, and means on the riveter operable in a. step-by-step fashion to initiate operation of said control means from a normal to an intermediate position and also from said intermediate position to the fully actuated position.

9. A compression riveter completing a rivet installation in separate setting and heading stages of operation, comprising a fluid pressure respon- 

